Switch mechanism for overhead trolley



March 31, 1970 HEZIBERG 3,503,336

SWITCH MECHANISM FOR OVERHEAD TROLLEY 2 Sheets-Sheet 1 Filed Sept. 15. 1967 INVENTOR LEIF HEILBERG BY W I IVE) United States Patent 3,503,336 SWITCH MECHANISM FOR OVERHEAD TROLLEY Leif Heilberg, San Francisco, Calif., assignor to Cincinnati Butchers Supply Company, Cincinnati, Ohio, a corporation of Ohio Filed Sept. 15, 1967, Ser. No. 668,315 Int. Cl. B61b /00; E0lb 25/26 U.S. Cl. 104103 12 Claims ABSTRACT OF THE DISCLOSURE The switch elements for directing a trolley along one of two alternative routes, incorporate a spring-biased mechanism operative subsequently to an initial manual displacement of a switch element control lever, for ensuring snap-action instant disposition of the switch elements to one or the other of two home positions providing continuity of trackage for the trolley advancement. The switching is performed instantaneously and without frictional lag, so as to minimize the possibility of trolley derailment.

The present invention relates to a switch mechanism for overhead trolleys, and constitutes an improvement over the mechanism disclosed by the United States Patent of Sidney LeFiell, No. 2,746,397, dated May 22, 1956.

An object of the invention is to provide a simplified yet highly dependable and durable switch mechanism, whereby a trolley adapted to suspend and transfer a heavy object or load, may be switched from a main track to a spur track, or vice versa, with ease and dispatch.

Another object of the invention is to provide a mechanism of the character stated, wherein are effected substantial savings of weight, installation and maintenance expense, and costs of time, labor, and materials in the manufacture and assembly thereof.

A further object is to reduce to a minimum the number of working parts in a mechanism of the character stated; to conserve installation and working space; and to ensure smooth and instantaneous dependable operation beneficial to the human operator from the standpoint of minimizing fatigue and operating skill.

Another object of the invention is to minimize the possibility of trolley derailment by providing for instantaneous snap-action switching.

The foregoing and other objects are attained by the means described herein and illustrated upon the accompanying drawings, in which:

FIG. 1 is a perspective view of the improved switch mechanism applied to a main overhead track and a spur track, with the main track switch closed and the spur track switch open.

FIG. 2 is a view similar to FIG. 1, showing the main track switch open and the spur track switch closed.

FIG. 3 is a top plan view of FIG. 1, with the switch elements disposed in the FIG. 1 position.

FIG. 4 is a side elevational view taken on line 44 of FIG. 3.

FIG. 5 is a cross-section taken on line 5-5 of FIG. 3.

It is common practice to employ overhead conveyors in various types of warehouses, meat packing plants, and other establishments wherein objects are suspended and transferred by means of wheeled trolleys. The conveyors may consist of horizontal and sometimes inclined tracks over which the trolleys are movable to carry suspended objects along a track circuit which may include spur tracks for delivering the objects to various stations or locations 011 the main line of track. Where spur tracks are employed, it is necessary to install switching mechanisms in the main line of track for diverting the trolleys and their loads to the various stations or locations. A

switching mechanism for the purpose constitutes the subject matter of the present invention, with a realization of the several objects above stated.

When a switch is said to be open, in the following explanation, it is meant that a trolley cannot pass over the track controlled by the switch; and conversely, when a switch is said to be closed, a trolley may pass uninterruptedly over the track supporting it. Thus, in FIG. 1, the main track switch element 8 is shown closed with relation to main track 10, and the spur track switch element 12 is open relative to spur track 14. For purposes of explanation only, 10 denotes the main track while 14 denotes a spur track, the understanding being that in practice, either may be considered the main track.

The reference numeral 16 indicates one of many hangers used for suspending the main track from an overhead beam or support, the hanger being olfset as usual to permit a trolley to pass along the track. Portions of spur track 14 may be similarly suspended. The tracks 10 and 14 usually are substantially horizontal, although not necessarily so.

Track 10 may be cut away to provide a longitudinal ledge 18 disposed at a lower elevation than the trolleyengaging upper edge 20 of the track, and upon ledge \18 may rest the switch element 8 rendering the main track continuous so that a trolley 22 may traverse the length of the main track. At times, switch element 8 may be displaced upwardly, as in FIG. 2, while at the same time the switch element 12 is lowered onto ledge 18 for guiding a trolley onto spur track 14 from the right of FIG. 2. In practical use, one or the other of switch elements 8 or 12 will be supported upon a portion of ledge 18 alternatively, according to FIGS. 1 and 2, and means is provided for so placing the switch elements in operative position upon said ledge, in alternation.

Referring to FIGS. 1 and 2, the numeral 24 indicates a control lever or actuating member having an elongate head 26 pivoted intermediate its opposite ends upon one side face of track 10, as by means of a bolt or pivot member 28. Head 26 may be welded to lever 24 as shown, or these parts 24 and 26 may be formed from a single piece of metal. Head 26 may lie flatwise with relation to track 10, and is subject to limited rocking movement about pivot 28 as the lever swings between limits denoted by the full lines and the broken lines 24, of FIG. 4. Upon one end 30 of head 26 may be welded or otherwise fixed, as at 32, one end of switch member 8.

From the foregoing, it will be understood that partial counter-clockwise rotation of head 26- from the position of FIG. 1 to the position of FIG. 2, will result in elevating the switch element 8 from the ledge 18 of track 10 to the inclined position of FIG. 2; and conversely, subsequent partial rotation of head 26 in the opposite direction will serve to replace switch element 8 upon the ledge, as in FIG. 1. Pivot 28 is to be located close to one end of ledge 18, as shown.

Switch element 12 is adapted to be swung about a pivot 34 on track 14, in much the same manner as is explained above concerning switch element 8. Track 14 may be cut away to form a short ledge 36 at the track end, and upon which ledge may be lowered the switch element 12. The free end 38 of switch element 12 is long enough to reach and rest upon the ledge 18 of track 10, and to bridge the gap between track 10 and the adjacent end 40 of track 14, so that a trolley movable from the right end of track 10 and onto switch element 12 will be guided smoothly onto the spur track 14, see FIG. 2.

Switch element 12 may have one end thereof welded at 42, or otherwise secured, to one end of a rocker 44 which rocker is pivotally connected by pivot 34 to one side face of spur track 14. The free end 46 of rocker 44 has a pivotal connection with the lower end of an upright link 48 to be longitudinally reciprocated for elevating and lowering the switch element 12 about its pivot 34. At pivot 34, the rocker 44 may flatly abut one side face of track 14.

A rigid yoke 50 includes a header 52 and depending legs 54, 56, which are fixedly mounted upon the side faces of tracks and 14, respectively, at the locations 58 and 60. Upon header 52 intermediate the legs 54 and 56, is provided a pivot 62 which rockingly supports an elongate bell crank 64. One end 66 of the bell crank has pivotal connection with the upper end of link 48, whereas the opposite end 68 thereof is pivotally connected to the upper end of an upright operating pitman 70. The lower end of pitman 70 may be formed into a circular loop 72 which embraces a stud 74 extended laterally from the swingable end 76 of control lever head 26.

It will be understood from the foregoing, that rocking movements of control lever head 26 induced by the swinging of control lever 24 between the limits indicated upon FIG. 4, will be translated through stud 74 to operating pitman 70, for rocking the bell crank 64 about its pivot 62. The bell crank in turn will reciprocate the link 48 to eflfect rocking movement of element 44 which elevates and lowers the switch element 12 between the limits indicated upon FIGS. 1 and 2, or FIG. 5.

The control lever 24, FIG. 4, is to assume either one of two positions at opposite sides of a vertical line passing through pivot 28, in order to ensure the closing of one or the other of switch elements 8 or 12. That is to say, the control lever 24 is never to remain in an intermediate position at which both switches may be open. To ensure disposition of the control lever 24 to one or the other of its extremes, there is provided a snap-action switch element biasing device which acts instantaneously to kick the control lever off the dead-center position and into one of the extreme limit positions of FIG. 4.

As is best illustrated by FIG. 4, the snap-action biasing device may comprise a reasonably strong compression spring 80 having one end thereof seated upon a stationary spring seat 82, and piloted by a stud 84 surrounded by the spring end. The axis of the pilot stud is directed substantially toward control lever pivot 28, and said axis may be referred to as the dead center axis of the biasing device.

The stud 74 carried by control lever head 26, is movable by lever 24 to positions at opposite sides of the dead center axis of the biasing device, as indicated by the full lines and the broken lines 74 of FIG. 4. Stud 74 may carry a spring pilot stud 86 surrounded by the upper end of spring 80, and having a seat about said stud 86 against which the upper end of the spring may bear at all times. Between the pilot studs 84 and 86, the spring 80 is kept under rather forceful longitudinal compression. Pilot stud 86 may be formed as part of a collar 88 which is rotatable upon pivot stud 74, so that pilot stud 86 may oscillate slightly with a change of its axial direction of extension as head 26 rotates upon its pivot 28. This is shown in FIG. 4 by full lines 86 and broken lines 86, which denote the upper pilot stud in two positions at opposite sides of the dead center axis passing through the parts 84 and 28.

With reference to FIG. 4, control lever 24 is shown in position to close the switch element 8 upon track 10, with spring 80 acting to yieldingly bias to such position the parts 8 and 24. That is, the spring is under compression tending to rotate head 26 in clockwise direction about its pivot 28. Clockwise rotation of head 26 is shown limited by switch element 8 abutting shelf 18.

Assuming now that an attendant decides to actuate the switch mechanism and thereby direct a trolley from track 10 onto spur 14, he will impose a sharp downward pull on cord or flexible pull member 90 (FIG. 4), to displace control lever 24 toward the right about pivot 28. Such displacement of lever 24 Will be accompanied by inertia of the lever sufficient to carry stud 74 to and beyond the dead center line connecting pilot 84 and pivot 28, thereby changing the direction of extensile expansion of spring 80 to rotationally impel head 26 and its associated lever 24 instantly to the limit of movement indicated by broken lines 26 and 24 upon FIG. 4. Switch element 8 thereupon will be displaced to the broken line open position 8 of FIG. 4, while at the same time the switch element 12 will be closed between tracks 10 and 14 (FIG. 2), by the ac tion of bell crank 64 initiated by pitman moving with head 26 and stud 74.

To subsequently close the switch 8 and open the switch 12, the attendant may exert a sharp downward pull upon the cord or pull member 90 at the right of FIG. 4, causing control lever 24 to pass the vertical position thereof by inertia, whereupon spring will re-act to impel lever 24 to the full line position of FIG. 4.

From the foregoing explanation, it will be understood that spring 80 acts to impose an off-center throw of lever 24 instantly to either of the two positions indicated upon FIG. 4, once the lever movement has been properly initiated manually by an attendant. The bell crank 64 and its associated linkage ensures the closing of one switch while the other switch is open, so that trolleys such as 22 will advance either straight-away along track 10 or be shunted onto spur track 14, depending upon the disposition of the switching elements 8 and 12. Any intermediate disposition of the switching elements is prevented by the off-center biasing action of spring 80 upon the control lever and the switching elements linked thereto through the bell crank assembly. Otherwise stated, the switch elements and control lever 24 are spring-biased to either one of two home positions, by the off-center throw device which incorporates spring 80.

The reference numeral 91 indicates a rigid stationary bracket welded or otherwise fixed to yoke leg 54, or to track 10, for stationarily supporting the seat member 82 for spring 80.

It is to be understood that various modifications and changes may be made in the structural details of the apparatus without departing from the spirit of the invention.

What is claimed is:

1. A switch mechanism for directing a trolley alternatively along an overhead main track or an adjacent overhead spur track having an end disposed near the main track, said main track being cut away to form a longitudinal upper ledge, and said spur track having a longitudinal upper ledge at said end thereof, said switch mechanism comprising: an elongate main track switch element having one end mounted for pivotal movement upon the main track adjacent to one end of the main track ledge, for guiding said switch element from an operative position upon the main track ledge to an inoperative position of inclination remote from said main track ledge; an elongate spur track switch element having opposite ends, and means pivotally mounting one of said opposite ends upon the spur track for alternative disposition of the spur track switch element from an operative position at which the spur track switch element overlies the ledge of the spur track and a portion of the main track ledge, to an inoperative position of inclination remote from both ledges; rockable linkage means connected to both of said switch elements, operative to simultaneously move one switch element to operative position while displacing the other switch element to inoperative position; and actuating means including an operating lever pivotally mounted to one of said tracks and having a movable spring seat carried thereby and said main track switch element fixedly attached directly thereto, a fixed spring seat connected to one of said tracks in spaced relation to said movable spring seat, a compression spring mounted between said spring seats, said movable spring seat moving overcenter with respect to said compression spring as said lever means is manipulated between its extreme positions whereby said compression spring imparts a snap action to said switch elements and resiliently holds said elements in their respective operative positions.

2. The switch mechanism as specified by claim 1, wherein is included a rigid yoke fixedly mountable upon at least one of the tracks, and means on the yoke for rockingly supporting the linkage means.

3. The switch mechanism as specified by claim 1, wherein is included an elongate control lever having a free end and a pivoted end; means pivotally mounting said pivoted end upon one of the tracks, with the free end thereof swingable to limits of movement at opposite sides of a vertical line passing through the control lever pivot; means connecting the control lever to the linkage means for enforcing actuation of said linkage means concurrently with swinging movements of said control lever between the limits of movement of said lever, said spring being operative to yieldingly drive the control lever in opposite directions from the aforesaid vertical line passing through the control lever pivot.

4. The switch mechanism as specified by claim 3, wherein the spring directs its driving force upon the control lever adjacent to the control lever pivot.

5. The switch mechanism as specified by claim 3, wherein the free end of the control lever depends from the control lever pivot, and includes means for manually imparting inertia to said lever for carrying the lever movement from one limit of disposition to and beyond the aforesaid vertical line passing through the control lever pivot.

6. The switch mechanism as specified by claim 4, wherein the free end of the control lever depends from the control lever pivot, and includes means for manually imparting inertia to said lever for carrying the lever movement from one limit of disposition to and beyond the aforesaid vertical line passing through the control lever pivot.

7. The switch mechanism as specified by claim 6, wherein is included a rigid member fixedly mountable upon at least one of the tracks, and means on said rigid member for rockingly supporting the linkage means.

8. A switch mechanism for directing a trolley alternatively along a substantially horizontal overhead main track or an adjacent substantially horizontal spur track having an end disposed near the main track, said main track being cut away to form a longitudinal upper ledge, and said spur track having a longitudinal upper ledge at said end thereof, said switch mechanism comprising: an elongate spur track switch element having opposite ends, and means pivoting one of said opposite ends upon the spur track for alternative disposition of the spur track switch element from an operative position overlying the ledge of the spur track and a portion of the main track ledge, to an inoperative position remote from both ledges; an elongate control lever having a free end, and an opposite end including a head fixed relative to the lever; means pivoting said head upon a side of the main track, with the free end of the lever pendent therefrom and swingable between limits of movement at opposite sides of a vertical line passing through the control lever pivot; an elongate main track switch element having an end fixed to said control lever head and movable therewith for shifting said main track switch element from an operative position overlying the main track ledge, to an inoperative inclined position remote from said main track ledge; an elongate bell crank, and a stationary support therefor; means intermediate the ends of the bell crank for pivotally mounting the bell crank upon said support for rocking movement, with opposite ends of said bell crank traveling in opposite directions toward and from the tracks; a link connecting one end of the bell crank to the spur track switch element adjacent to the pivot of the latter, for translating rocking movement of the bell crank to movement of the spur track switch element between the operative and the inoperative positions of the latter; a pitman connecting the remaining end of the bell crank to said control lever head at a location adjacent to the head pivot, whereby movements of the control lever and head in disposing the main track switch element to the operative and inoperative positions of the latter, are translated by said pitrnan into rocking movements of the bell crank; a laterally extending stud on the control lever head, said stud being spaced from the pivot of said head, said stud being spaced from the pivot of said head opposite the main track switch element carried by said head; a stationary spring seat fixed relative to the main track; a movable spring seat carried by the laterally extending stud; a compression spring having opposite ends seated upon the fixed seat and the movable seat, with the spring partially compressed between said seats; the movable seat being shiftable to opposite sides of a dead-center line passing through the said movable seat and the pivot of the control lever head, incident to shifting the free end of the control lever from one limit of its movement toward the opposite limit thereof.

9. The switch mechanism as specified by claim 8, Wherein is included a flexible pull member fixed to the free end of the control lever for exerting a downward manual sharp pull on said lever while the lever rests at one of its limits of movement remote from the vertical line through the control lever pivot, thereby to generate a force of inertia in said lever for impelling said lever to and beyond the vertical line aforesaid.

10. The switch mechanism as specified by claim 8, wherein the stationary spring seat includes an elongate pilot stud surounded by an end of the compression spring, said pilot stud having a longitudinal axis directed substantially toward the axis of the control lever head pivot.

11. The switch mechanism as specified by claim 9, wherein the sationary spring seat includes an elongate pilot stud surrounded by an end of the compression spring, said pilot stud having a longitudinal axis directed toward the axis of rotation of the control lever head.

12. The switch mechanism as specified by claim 8, wherein the control lever head supports the main track switch element at all times in a vertical plane which includes the main track.

References Cited UNITED STATES PATENTS 1,670,472 5/ 1928 Millward 246-410 2,761,029 8/1956 Peabody 2671 XR 2,746,397 5/1956 Le Feill 104101 2,944,491 7/ 1960 Le Feill 104--103 3,063,384 11/1962 Sackett 104103 ARTHUR L. LA POINT, Primary Examiner 

